Electrical apparatus employing dielectric fluids



Aug. 2, 1960 R. M. MURCH 2,947,926

ELECTRICAL APPARATUS EMPLOYING DIELECTRIC FLUIDS Filed Nov. 23, 1956 INVENIYTOR. RUBERf M. Ml/RC/l ATTORNEY United States Patent: Oilice DZELECTRIC FLU; is

1 Claim. (Cl. 3l7-Z58) This invention relates to electrical apparatus employing dielectric fluids.

Silicone fluids have long been Well known as dielectric fluids as shown in US. Patent No. 2,377,689. These silicone dielectric fluids have shown advantages over fluids in that the silicones have good thermal and chemical stability, at low temperature-viscosity curve and low power loss or dissipation. However, the dielectric strength of the presently employed silicone fluids has a range from 2.2 to 3.3. Consequently, there has been a search for a silicon dielectric fluid which has a higher dielectric constant while retaining the other favorable characteristics of such fluids.

The object of this invention is to provide improved electrical apparatus This invention relates to an electrical apparatus comprising elements in spaced relationship having between them a diiierence in electrical potential and between said elements a dielectric iiuid consisting essentially of The fluid employed in this invention is known and disclosed in US. Patent No; 2,571,090. For a fuller understanding of the nature and objects of this invention, reference may be had to the following detailed description taken in conjunction with the accompanying drawing in which:

Figure 1 is a cutaway section of an isometric View of a capacitor; and

Figure 2. shows a variation in the type and relationship of the elements of the apparatus of this invention.

Referring to Figure l of the drawing, a capacitor is shown with a casing 3 in which plates 4, made of some suitable conductin material such as aluminum foil and the like, are suspended completely immersed and separated by the liquid dielectric fluid 5 of this invention. Terminal leads 6 are supplied for applying potential to the elements. in Figure 2 another embodiment of this invention is shown where the elements of different potential are arranged as in a coaxial cable, i.e. concentric cylindrical elements 7 and 8. The inside cylinder 8 may be solid or hollow.

The elements of this invention can be spaced with porous separators which are soaked with the dielectric fluid of this invention. Furthermore, the dielectric fluid or" this invention can be mixed with other dielectric fluids both silicone and organic. However, it must be kept in mind that too high a proportion of organic dielectric fluid will minimize the effect of the dielectric fluid of this invention. Stabilizers can also he used in the system. The elements of the apparatus of this invention 2,947,926: l atented Aug. 2, 1960 may the in any form such as sheets, cylinders, coils, spheres and the like. It has been found that electrical apparatus of this invention are two to four times as eflicient as previously employed apparatus. This is exd by the fact that equal capacitance is obtained reduction of the eflective area of the conducting elements and the distance between them. Thus, a decrease in apparatus volume results without a loss in efficiency. This invention applies to such electrical apparatus as transformers, capacitors, coaxial cables, switches, fuses, reactors, regulators, circuit breakers and similar equipment.

The following examples are illustrative and are not intended to limit the present invention which is properly set forth in the claim.

Example 1 The fluid of this invention was tested in a Balsbaugh cell 2TN25 for dielectric factor and dissipation factor at varying temperatures and frequencies. At 20 C., at 100 cycles per second the dielectric constant was 9.5. At the same temperature at l0,000 cycles er second the dielectric str ngth was 9.2. For the temperature range 0 to 100 C. the dielectric constant was the same for all frequencies tested, i.e., 100 to 100,000 cycles per second. Temperature in C.: Dielectric constant 0 9.0 25 8.3 50 7.6 7.0 6.5

cycles per second the same tempera- Example 2 The dielectric fluid of this invention was tested at 23 C. for fast-rise direct current strength in a cell containing 2 one-half inch diametric steel spherical electrodes spaced 50 mils apart. The average brealodown voltage was found to be 500 volts per mil.

These tests prove that an electrical apparatus of this invention such as a capacitor is two to four times as eflicient as apparatus employing other siloXane fluids.

That which is claimed is:

An electrical apparatus comprising elements in spaced relationship having between them a difierence in electrical potential, there being between said elements a dielectric fluid consisting essentially of CFs Me SiO 4 References Cited in the file of this patent UNITED STATES PATENTS 2,571,090 Kohl Oct. 16, 1951 2,636,896 Frost Apr. 28, 1953 2,802,017 Frost et a1. Aug. 6, 1957 

